Exhaust-gas cooler for an internal combustion engine

ABSTRACT

An exhaust-gas cooler for an internal combustion engine has a plurality of flow channels which conduct exhaust gas. The flow channels are arranged within a housing ( 1 ) and are in thermal exchange with a fluid for cooling the exhaust gas. At least one filter member ( 3 ) for filtering particles from the exhaust-gas flow is integrated structurally into the exhaust-gas cooler.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of European patent application no. 08291142.1, filed Dec. 3, 2008, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to an exhaust-gas cooler for cooling the exhaust gas of an internal combustion engine.

BACKGROUND OF THE INVENTION

Systems for exhaust-gas recirculation are known wherein the exhaust gas is cooled in an exhaust-gas cooler and is subsequently fed to the combustion air of the engine either downstream of a turbocharger (high-pressure EGR) or upstream of a turbocharger (high-pressure EGR). Exhaust-gas recirculation systems are often utilized for reducing toxic substances from diesel engines wherein, in addition, a particle filtering of the exhaust gas is provided. One such particle filter is routinely designed as a regenerative filter and a cleansing of the filter takes place via controlledly triggered burn-off phases. However, especially in such phases, larger particles can loosen even generally because of construction and these larger particles can endanger the turbocharger, for example, in the case of the low-pressure EGR. It is therefore known to provide a filter member which is structurally separate and arranged downstream of the actual particle filter. This separate filter member is not designed to be regenerative but traps at least larger particles in a reliable manner.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an exhaust-gas cooler for an internal combustion engine with which an integration of components is made possible.

The exhaust-gas cooler of the invention is for an internal combustion engine. The exhaust-gas cooler includes: a housing; a plurality of flow channels for conducting exhaust gas; the flow channels being arranged in the housing to facilitate a thermal exchange with a fluid for cooling the exhaust gas; and, a filter member structurally integrated into the exhaust-gas cooler for filtering out particles from the flow of exhaust gas.

An additional component assembly, which has to be integrated into the exhaust-gas tract, is made unnecessary by the integration of the filter member into the exhaust-gas cooler. The cooling fluid is preferably a liquid coolant, for example, a low-temperature cooling loop and/or a cooling loop of the internal combustion engine.

In a preferred embodiment, the filter member is mounted within the housing and the fluid especially flows through the housing. In this way, little space for structure is needed. In a simple manner, the fluid can flow around the filter member and so enable the filter member to contribute to the cooling of the exhaust gas.

In a preferred embodiment of the invention, the exhaust gas flows through the exhaust-gas cooler at least once in a toward direction and in a return direction. The filter member is provided in at least one of the two directions (toward direction or return direction). Such an exhaust-gas cooler can be configured as a U-flow cooler or even as a Z-flow cooler. The structural size remains compact in longitudinal direction because of the redirection. In a preferred detail configuration, especially a single flow channel of the toward direction is configured as a tube part defining the filter. A plurality of flow channels of the return direction is configured as a bundle of exchanger tubes. In addition to the simple and compact structural configuration, this disposition of the filter affords the advantage that filtering takes place by the filter member upstream of the exchanger tubes so that the latter cannot be blocked by larger particles.

In the interest of a simple manufacture, it is further advantageous to accommodate the tube part and/or the bundle of exchanger tubes in the end base parts. Especially, the same base parts can each hold the filter member as well as the exchanger tubes.

According to another feature of the invention, a redirect zone for changing the direction of flow of the exhaust gas is configured at an end face of the exhaust-gas cooler.

The filter member can be simply and cost effectively configured as a tube part having the filter insert fixed therein. The filter insert can, for example, be fixed by welding or soldering in the tube part.

It is generally advantageous to provide a bypass line, through which exhaust gas can flow, on the exhaust-gas cooler for operating modes such as a cold start phase. The bypass line branches off especially downstream of the filter member and upstream of a plurality of flow channels. In this way, a filtering of the gas flow takes place at all times even when the exhaust gas flows through the bypass line which is not cooled or cooled only to a slight extent.

Generally, it is preferable when the filter member is configured as a permanent filter not regenerable during operation. Depending upon requirements, the filter member can be designed for the entire service life of the internal combustion engine or can be designed as an exchangeable part which is subject to wear.

In a generally preferred embodiment, the exhaust-gas cooler is configured for mounting downstream of a particle filter. The particle filter assumes the task of a regenerable fine-particle filter and the filter member has primarily the task of a protective filter for larger particles which occur, for example, during a burn-off phase of the particle filter and could damage a downstream turbocharger. For the same reason, it is advantageous to configure an exhaust-gas cooler of the invention for arranging the same upstream of a turbocharger (low-pressure exhaust-gas recirculation).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawings wherein:

FIG. 1 shows a perspective view of an exhaust-gas cooler according to the invention;

FIG. 2 shows a perspective view of the exhaust-gas cooler of FIG. 1 without a connecting region;

FIG. 3 shows an enlarged detail cutaway view of the exhaust-gas cooler of FIG. 2;

FIG. 4 is a schematic showing a cutaway view of another embodiment of an exhaust-gas cooler according to the invention; and,

FIG. 5 shows a variation of the exhaust-gas cooler of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The exhaust-gas cooler of the embodiment shown in FIGS. 1 to 3 includes a housing 1 through which a cooling liquid can flow in the manner of a water jacket (coolant connections not shown). The cooling liquid can be connected to an engine cooling loop or even to a separate low-temperature cooling loop.

In the housing 1, a bundle of exchanger tubes 2 as well as a tube-shaped filter member 3 are arranged parallel to each other and each define a cooling channel for the exhaust gas of an internal combustion engine. In the present examples, the engine in each case is a diesel engine for a motor vehicle, especially, an automobile.

The filter member 3 includes a tube part 3 a as well as filter insert 3 b which is fixed via soldering or welding. The filter insert 3 b is shown schematically in FIGS. 4 and 5. The exchanger tubes 2 as well as the tube part 3 a of the filter member 3 are each fixed in the same perforated base part 4, for example, by welding.

The exhaust-gas cooler is designed as a U-flow cooler and has an inlet end onto which, as shown in FIG. 1, a connecting member 5, which has a feed 5 a and a discharge 5 b for the exhaust gas, is attached with threaded fasteners to the base part 4.

A redirect zone 6 is fixed on the opposite-lying end of the flow channels on the base part located there. The exhaust gas therefore flows through the exhaust-gas cooler first in a toward direction through the filter member 3 and is then redirected by 180° in redirect zone 6 and flows through the exhaust-gas cooler in the return direction through the exchanger tubes 2.

The redirect zone 6 is configured as a hollow chamber into which, in addition, a bypass channel 7 opens. In this way, for example, in a cold start phase, the exhaust gas first flows through the filter member 3 and is then conducted away, without further cooling, through the bypass channel 7. The greater part of the exhaust gas cooling takes place via the bundle of exchanger tubes 2 whereby a low heat removal is provided also through the filter member 3 around which coolant flows.

The exhaust-gas cooler according to the present embodiments comprises substantially corrosion resistant steel. At least some parts can be made of aluminum or plastic (for example, the water jacket 1) depending upon the exhaust-gas temperature and the design.

The exhaust-gas cooler is tied into an overall system wherein the exhaust-gas recirculation is configured as a low-pressure recirculation. In flow direction, a regenerable particle filter is mounted upstream of the exhaust-gas cooler and the air end of an exhaust-gas turbocharger is arranged downstream. The admixing of the exhaust gas to the combustion air of the engine takes place here ahead of the compression by the turbocharger.

The filter member 3 is not configured as a regenerable permanent filter designed for the entire service life of the vehicle. A mesh size of the filter is correspondingly so configured that only particles of a size which could damage the turbocharger are filtered out.

In the embodiment of FIG. 4, the directions of the exhaust-gas flow are indicated by arrows. In addition to a different arrangement of the exchanger tubes, the difference to the first embodiment is that no bypass channel is provided.

The variation of FIG. 5 corresponds to the example of FIG. 4 except for the arrangement of the exchanger tubes. In FIG. 5, the two end face base parts 4 and the hollow space of the redirect zone 6 are shown. Only one of the exchanger tubes 3 is shown to provide a better overview.

It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims. 

1. An exhaust-gas cooler for an internal combustion engine, the exhaust-gas cooler comprising: a housing; a plurality of flow channels for conducting exhaust gas; said flow channels being arranged in said housing to facilitate a thermal exchange with a fluid for cooling the exhaust gas; and, a filter member structurally integrated into said exhaust-gas cooler for filtering out particles from the flow of exhaust gas.
 2. The exhaust-gas cooler of claim 1, wherein said filter member is mounted within said housing.
 3. The exhaust-gas cooler of claim 2, wherein said housing is configured to conduct said fluid therethrough to facilitate said thermal exchange.
 4. The exhaust-gas cooler of claim 1, wherein said exhaust gas flows through said exhaust-gas cooler at least once in a toward direction and in a return direction; and, said filter member is disposed in at least one of said two directions.
 5. The exhaust-gas cooler of claim 4, wherein one of said plurality of flow channels conducts said exhaust gas in said toward direction; the remainder of said plurality of flow channels conducts the exhaust gas in the return direction and is configured as a bundle of exchanger tubes; and, said one flow channel is a tube part defining said filter member.
 6. The exhaust-gas cooler of claim 5, further comprising first and second end base parts; and, at least one of said one flow channel and said remainder of said flow channels being accommodated in said first and second end base parts.
 7. The exhaust-gas cooler of claim 5, said second end base part defining an end face of said exhaust-gas cooler; and, said exhaust-gas cooler further comprising a redirect zone configured at said face for redirecting the flow of exhaust gas from said toward direction to said return direction.
 8. The exhaust-gas cooler of claim 4, wherein one of said plurality of flow channels conducts said exhaust gas in said toward direction; the remainder of said plurality of said flow channels conducts the exhaust gas in said return direction; said one flow channel is configured as a tube part; and, said filter member is configured as said tube part having a filter insert fixedly disposed therein.
 9. The exhaust-gas cooler of claim 5, further comprising a bypass line for conducting exhaust gas therethrough; and, said bypass line branching off downstream of said filter member and upstream of said plurality of said remainder of said flow channels.
 10. The exhaust-gas cooler of claim 1, wherein said filter member is configured as a permanent filter not regenerable during operation.
 11. The exhaust-gas cooler of claim 1, wherein said internal combustion engine includes a particle filter; and, said exhaust-gas cooler is configured to be mounted downstream of said particle filter.
 12. The exhaust-gas cooler of claim 1, wherein said internal combustion engine includes a turbocharger; and, said exhaust-gas cooler is mounted upstream of said turbocharger.
 13. The exhaust-gas cooler of claim 4, wherein a single one of said plurality of flow channels conducts said exhaust gas in said toward direction; the remainder of said plurality of flow channels conducts the exhaust gas in the return direction and is configured as a bundle of exchanger tubes; and, said single flow channel is a tube part defining said filter member. 